Experimental study on convective heat transfer in alternating elliptical axis tubes

Experiments are carried out on the convection inside a novel alternating elliptical axis tube. The unified correlations of heat transfer and flow resistance for 500 < Re < 5 × 104 are obtained from the experimental results. The experiments show that the heat transfer can be greatly enhanced with less flow resistance increment compared with other enhanced elements. Analyses indicate that the mechanism for heat transfer enhancement is mainly due to the effect of the multi-longitudinal vortices induced by the cross-sectional change in the alternating elliptical axis tubes.